Electron-discharge device



Aug; 6, 1929'. w. c. WHITE ELECTRON DISCHARGE'DEVICE Filed June 18. 1926 In vennor-z William Qwhite;

His Az-Lcrneu Patented Aug. 6, 1929.

UNITED STATES PATENT OFFICE.

WILLIAM G. WHITE, OF SGHENEC'IADY, NEW YORK, ASSIGNOR T0 GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

ELECTRON-DISCHARGE DEVICE.

Application filed June 18,

My present invention relates to improvements in electron discharge devices and more particularly to means for preventlng short circuits between the cathode and anode elements of high power, high voltage rectifiers employing elongated filamentary cath ode elements.

In the employment of rectifiers of the above type the filament or cathode element is arranged close to the anode or plate memher and as a result if the rectifier 1s sub ected to vibration there is a tendency to form a short circuit between the filament and plate. The electromagnetic repulsive force between the two spans of a V filament and the electrostatic attraction between the plate and filament also tend to bow the filament spans and may cause short circuit between the electrodes. Furthermore, when such a filament is heated it becomes bowed and in this manner may cause a short circuit and ultimate failure of the rectifier tube. I have found that the failure of the rectifier tube due to short circuits caused either by vibration or heating of the filamentary electrode may be prevented by restricting the motion of the filament at a point or points intermediate the ends thereof.

The novel features, which I believe to be characteristic of my invention, are set forth with particularity in the appended claims. My invention itself, however, will best be understood by the following specification taken in connection with the accompanying drawing in which Figure l-shows an elevation partly broken away of an electron discharge device embodying the features of my invention, while Figure 2 is a detail perspective view of the means for preventing bowing or vibration of the filamentary electrode.

Referring to the drawing, I have indicated at 1 an electron discharge device, in the present instance a rectifier of the two element type comprising an evacuated glass envelope or container 2 and cooperating electrodes 3 and 4t mounted at opposite ends of the container 1. The filamentary electrode 3 is arranged within the hollow anode 4 and is provided with a pair of heavy tungsten lead wires 5, which extend through the usual glass stem 6. A supporting metal rod 7 of indicated in Figure 2 and serve to prevent vibration or bowing of the filament 3.

Insulator 8 is placed on rod 7 substantially midway between the ends of the filament 3 and is maintained in that position by means of a pair of metal buttons 10 and 11, which are welded to rod 7 after the insulator is positioned thereon. Although other refractory oxide insulators such as magnesia may be employed, I have found that an alumina insulator gives very good results, as the amount of gas liberated from alumina is rel atively small and it retains its high insulating value when subjected to very high temperatures.

What I claim as new and desire to secure by Letters Patent of the United States, is

1. In an electron discharge device, an elongated filament, metallic supporting means for the filament, an alumina disk mounted on the supporting means, and metallic means attached to said disk and engaging said filament at points intermediate its ends.

2. In an electron discharge device a filamentary carthode, a metallic supporting stem for the cathode, an alumina disk slidably mounted on the stem, means for maintaining the disk in position on the stem, said disk being provided with means adapted to engage the cathode at a point intermediate its ends.

3. In an electron discharge device, an elongated filamentary cathode and a cooperating hollow anode, a metallic supporting stem for the filament, means for restricting the vibration of the filament, said means comprising an insulating disk mounted on the supporting stem and provided with means for engaging the cathode at a point intermediate the ends thereof.

In witness whereof, I have hereunto set my hand this 17th day of June, 1926.

WILLIAM C. WHITE. 

